FIG. 1 shows a section through part of a conventional hand dryer, sold under the model name AB01 as part of the Dyson Airblade® range of hand dryers. This type of hand dryer is described in some detail in European Patent EP1909627. It works by forcing the drying air through two opposing, thin air slots—each less than 1 mm wide—to create opposing thin sheets of high velocity air, or “air-knives”, which act to strip water from the front and backs of a user's hands as they are ‘dipped’—palms flat—between the opposing air slots.
The part a shown in FIG. 1 is one of the so-called air-knife assemblies on the hand dryer. There are two of these air-knife assemblies, one forming each of the two opposing thin air slots. Each air-knife assembly a incorporates a nozzle b, which includes the respective air slot c and which connects to the end of a main air duct d. The nozzle b comes in two moulded parts e, f which are then assembled together to form the air slot c (FIG. 3). This lends itself to convenient injection-moulding of the two parts e, f but makes it difficult accurately to control the width W of the slot c due to tolerance stacking in the final assembly of the parts e, f.